Blade release mechanism for sedimentation units



Dec. 21, 1943. 5 BQUSMAN 1 '2, 337,226

BLADE RELEASE MECHANISM FOR SEDIMENTATION UNITS Filed Aug. 22, 1942 2 Sheets-Sheet 1 SAMUEL I. OR.

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a tic/139a Dec. 21, 1943- s. l. BOUSMAN BLADE RELEASE MECHANISM FOR SEDIMENTATION UNITS 2 Shets-Sheet 2 Filed Aug. 22, 1942 SA UEL I. BOUSMAN INYENTOR.

Patented Dec. 21, 1943 UNITED STATES PATENT OFFICE BLADE RELEASE MECHANISM FOR SEDIMENTATION UNITS Samuel I. Bousman, San Francisco, Calif., assignor to Western Machinery Company,

San

Claims.

This invention relates to improvements in sedimentation, or mixing units, such as classifiers and agitators of the type employed in metallurgical, chemical and sewage processing plants.

Apparatus of the type to which this invention relates are provided with one or more radial arms that rotate and which, in turn, are provided on their under surfaces with blades that are arranged at an angle to the direction of movement for the purpose of conveying the settled material to the center of the basin where the discharge is usually located.

Due to various causes the material that is being treated settles down onto the bottom of the basin where it condenses and becomes quite heavy which makes it necessary frequently to raise the blades in order to relieve the load so that operation may continue. If the apparatus for some reason must be shut down, the settling of the solids continues and unless some means is provided for raising the scraper blades, it becomes difiicult if not impossible to start the operation again.

In the ordinary center shaft driven machines, the release of the scraping apparatus is some times accomplished by raising the entire arm assembly by some suitable means such as a screw device attached to the top of the shaft or an arrangement whereby the arms lift themselves when the torque increases beyond a predetermined value. In large traction units or in mechanisms where the torque is applied at the center pier, the apparatus is often very large and the arms and driving cage assembly are heavy and cumbersome, making it very difficult and sometimes impossible to lift the whole assembly. In such apparatus relief from excessive loads has been obtained by raising the outer ends of the arms which, for this purpose, are hinged to the center or torque member. Since the material that settles near the outer periphery of the basin is small in comparison to that which settles near the center, it is evident that raising the arms at their outer ends is not very effective as the maximum torque resistance is located near the center of rotation Where the depth of the settled solids is the greatest.

It is the object of this invention to produce a scraping apparatus of the class above referred to which shall be so constructed that the blades on the arms can be raised individually and so that the blades near the center can be raised and lowered without making it necessary to lift the entire arm structure, this reduces the weights to be lifted to a minimum.

A further object of this invention is to provide a construction in which the blades will automatically raise when the load reaches a predetermined value, thereby making it possible to scrape irregular basin bottoms on which hard layers of solids may have accumulated as often happens in some chemical precipitation plants.

Another object of this invention is to produce a rigid structure that can be operated a considerable distance above the basin bottom with no danger of the arms coming into contact with the settled material.

The above and other objects that may become apparent as this description proceeds are attained by means of a construction and an arrangement of parts that will now be described in detail and for this purpose reference will be had to the accompanying drawings in which the preferred embodiment of the invention has been illustrated and in which:

Figure 1 shows a side elevation of an arm provided with scraper blades secured thereto in accordance with this invention, the arm has been shown as positioned in a basin which has been shown in radial section;

Figure 2 is a section taken on lines 2--2, Figure 1.

Figure 3 is a section taken on lines 3-3, Figures 1 and 2; and

Figure 4 is a diagram showing a modification of the lifting mechanism illustrated in Figure 3.

In the drawings reference numeral l0 desig nates a vertical center pier having an inlet opening II through which the material to be treated is fed. Near the top of the pier a transverse opening I2 is provided through which the ma? terial enters the basin. The top of the pier I 3 serves as a support for the supporting and driving mechanisms. Reference numeral l4 designates an annular ball race on which a bull gear I5 is supported; this gear has been shown as provided with radially extending lugs l6 that are perforated for the reception of the tension bar ll. Surrounding the pier is a cage which in the present embodiment has been shown as comprising four downwardly extending angle irons I8 that are connected by other angle irons l9 and 20. The radial arms carrying the scraper blades are attached to the cage that in turn is supported from the bull ring I5.

In the present application the exact means for rotating the arms about the pier has merely been indicated in a general way and will therefore not be described for the reason that the invention to which this application relates is independent of the specific means of supporting and rotating the arms.

The radial arms illustrated are formed from two angle irons 2| whose outer ends are connected by some suitable means such as a bolt 01' rivet 22. Secured to the inner surfaces of the vertical flanges are plates 23 that are connected with the flanges of the vertical cage members I8 by any suitable means such as bolts or rivets 24. A transverse angle iron 25 extends between the inner ends of the angle irons 2| forming a triangular structure such as shown in Figure 2. At each corner of the triangular structure illustrated in Figure 2 are upwardly extending angle irons 26 that taper upwardly and between the upper ends of which the downwardly extending flanges of the angle irons 21 are secured by suitable means. An angle bracket 28 is secured to the inner apex of the pyramidal arm structure and perforated for the reception of a bolt 29 whose inner end passes through an opening in the flange 30 of an angle iron connecting the cage members M3. Bolt 29 is threaded so that it may serve as means for raising and lowering the outer end of the arm structure to obtain a 'proper alignment with the bottom surface 3! of the basin. The bottom of the basin is slightly frustoconical and inclined towards the center where a channel 32, for the reception of the solids, is provided. The channel 32 is connected with a suitable outlet which has not been shown.

From Figure 1 it will be seen that the two top angles 21 are connected with the side angles 2! near their outer ends, thereby forming a very rigid triangular structure. Compression members 33 are provided at spaced intervals and these are connected by diagonal braces 34 so as to form a bridge-like assembly of great strength and rigidity.

Near the outer ends of the arms two stationary scraper blades 35 and 36 may be provided, and connected with the arms by suitable angle irons 31 and a curved plate 38, respectively. Blades 35 and 36 may, of course, be replaced by movable blades like those that will now be described. If vertically adjustable blades are substituted, the adjustable connection comprising elements 28, 29 and 30 can be replaced by a rigid connection.

Between the center supporting pier and the scraper blade 35, movable scraper blades 39 are provided. In the present embodiment three such blades have been shown. The scraper blades 39 are inclined with respect to their path or direction of movement, in such a way that the outer ends are in advance of the inner ends (see Fig. 2) whereby they move the material towards the center and are provided at their upper edges with rearwardly extending flanges 40, as shown in Figure 3, so as to give them strength and rigidity. Each blade is provided with two bars 4| whose forward ends are formed with openings for the reception of pivots or shafts 42. For the purpose of securing each hinge scraper blade assembly to the arm, the latter has been provided with diagonally arranged angle irons 43 whose downwardly extending flanges are perforated for the reception of the ends of the pivots or shafts 42. In order tosimplify the drawings the supporting means for the innermost scraper blade has not been shown complete, parts being omitted for the purpose of simplification. The manner of supporting this scraper blade is, however, the

same as that shown for the other blades illustrated.

Since the arms rotate in a clockwise direction, when viewed from the top and in the direction of the arrow R when viewed as in Figure 3, it is apparent that if solids accumulated to any considerable extent in front of the blades, the resistance thus encountered will be resolved into two forces, one of which tends to raise the blade upwardly from the bottom of the basin, and due to the construction shown, the blades will automatically adjust themselves during operation so as to limit the torque resistance to whatever amount is considered to be safe for the strength of the mechanism employed.

If the device is shut down for any reason, the automatic adjustment of the blades will, of course, not function and after the solids have settled about the blades, the latter would be so thoroughly embedded therein that the arms could not be rotated without first removing the solids in front of the blades.

For the purpose of raising the blades either after they have become embedded too solidly in the settlings to permit the mechanism to operate, or to prevent such embedding, means has been provided whereby the operator may raise the blades to a position where they will not extend into the more solid portions of the settlings. The mechanism provided for raising the blades will now be described with reference to the drawings.

Referring now more particularly to Figure 2, it will be seen that a shaft 44 is mounted for rotary movement in bearings 45 that are secured to the angle irons 43. An arm 48 is secured to the shaft 44 and so positioned that its outer end is directly above the corresponding scraper blade. A chain 41 connects the outer end of each arm with the corresponding scraper blade as shown in Figure 3. It is now evident that whenever the shaft 44 is rotated in a counterclockwise direction when viewed as in Figure 3, the arms 46 will move in a corresponding manner and lift the scraper blades. For the purpose of rotating the shaft 44 and thereby raising and lowering the scraper blades 39, the tension rod ll has been connected at its lower end 48 with the innermost crank arm 46. The upper end of the tension rod passes through an opening in the lug N3 of the bull wheel and is provided at its upper end with a nut 49 which rests on a spherical washer 53. By turning the nut 49 the shaft 44 can be rotated. Since the weight of the parts tendsto turn the shaft in a clockwise direction when viewed as in Figure 3, the blades will automatically move downwardly when the nut 49 is rotated so as. to permit the rod to move downwardly.

It'is evident from the above description when taken in connection with the drawings, that by the simple mechanism illustrated and described, the operator can raise and lower the scraper blades 39 so as to adjust their position with respect to the bottom of the basin for any purpose for which such adjustment may be found necessary or desirable.

In the present embodiment the mechanism for raising and lowering the blades has been shown as comprising a shaft 44 and a plurality of radial arms 43 and this is believed to be simple and substantial mechanism for the purpose described. It is evident, however, that the scraper blades may be raised by other and specifically different means and it is to be understood that the specific construction shown and described is illustrative only. H

In Figure 4 a diagrammatic representation of another lifting means has been shown in which a cable 5! has been shown as passing around pulleys 52 and as having its upper end connected with the lower end of a bolt Ila.

It is also evident that by changing the angular inclination of the blades 39 with respect to the bottom, the value of the force component tending to raise them can be varied so as to suit the automatic raising adjustment to the particular needs of the purpose for which the device is employed.

Instead of the means shown on the drawings for rotating shaft 44, the latter can be provided with a Worm gear and rod [1 with a worm, the latter being mounted for rotation instead of longitudinal movement as shown.

Where two or more arms are employed, the scraper blades are spaced in overlapping position as indicated by dotted lines in Figure 2.

Having described the invention what is claimed as new is:

1. A thickener comprising at least two arms mounted to turn about a vertical axis, a plurality of radially spaced scraper blades carried by each arm, and connected therewith for relative vertical movement, the blades being inclined with respect to a vertical plane containing the arm, in such a manner that the ends farthest from the center are nearer this plane than the other ends, whereby when the arm is rotated the blades will tend to move material towards the center of rotation, the outer end of each blade on one arm lapping the inner end of the next cooperatively adjacent blade on the other arm, and means for raising and lowering the blades comprising, a winch mechanism positioned near the center of rotation, and means operatively connecting the same with the blades.

2. A rotary stirring device comprising at least two arms mounted for rotation about a vertical axis, within the fluid body, a plurality of scraper blades positioned beneath each arm in cooperative overlapping relation with the blades on the angularly adjacent arm and mounted for vertical displacement within the body, about an axis positioned to the front and above the center of the blades, forming automatic means to effect a raising of the blades by varying resistance to their rotary motion, the blades being inclined with respect to a radius passing through them, the outer and the inner ends being respectively in front of and to the rear of the radius, means outside of the fluid body to eiTect said displacement, manually separate and independent of the automatic means, said means comprising a tension member extending upwardly from and connected with each scraper blade assembly, and means comprising a force multiplying mechanism for exerting a tensional force on said tension member.

3. A rotary stirring device comprising an arm mounted for rotation, about a vertical axis, within the fluid body, a plurality of scraper blades mounted beneath the arm in cooperative relation and mounted for vertical displacement within the body, about an axis positioned to the front and above the center of the blades, forming automatic means to effect a raising of the blades by varying resistance to their rotary motion, the blades being inclined with respect to a radius passing through them, the outer and the inner ends being respectively in front and in the rear of the radius, and means outside of the fluid body to effect said displacement, manually separate and independent of the automatic means, said means comprising a tension member extending upwardly from and connected with each scraper blade assembly, and means comprising a force multiplying mechanism for exerting a tensional force on said tension member.

4. A thickener comprising at least one arm mounted to turn out about a vertical axis, a plurality of radially spaced scraper blades carried by the arm, and connected therewith for relative vertical movement, the blades being inclined with respect to a vertical plane containing the arm, in such manner that the ends farthest from the center are nearer this plane than the other ends, whereby when the arm is rotated the blades will tend to move material towards the center of rotation, and means for raising and lowering the blades comprising, a winch mechanism positioned near the center of rotation, and means operatively connecting the same with the blades.

5. A rotary stirring device comprising an arm mounted for rotation about a vertical axis, a plurality of scraper blades mounted beneath the arm in cooperative relation, for vertical displacement within the fluid body, about horizontal axes fixed with respect to the centerline of the arm, positioned to the front of and above the centers of the blades, connecting means between the blades and the arm comprising at least two bars having one end rigidly connected with each blade in longitudinally spaced relation, the other ends being pivotally connected with the arm, forming automatic means to effect a raising of the blades by varying resistance to their rotary motion, the axes about which the blades pivot being inclined with respect to the center line of the arm passing through them, the outer and the inner ends being respectively in front of and in the rear of said center line, the scraper blades being substantially parallel with their axes of pivotation and spaced rearwardly therefrom.

SAMUEL I. BOUSMAN. 

